3 3D VIEW TOP VIEW FIGURE 2.4 Deformation of a lamina subject to temperature increase. equivalent to that for thermal strains [7,8](neglecting possible pressure dependence of moisture absorption). The constitutive relationship,when it includes mechanical-,thermal-,and moisture-induced strains,takes the following form [1,4] Su S12 0 01 ef] 「εT E2 S2 Sz 0 62 e 立 (2.18) Y12 0 0 S66 T12 0 where superscripts T and M denote temperature-and moisture-induced strains,respectively.Note that shear strains are not induced in the principal material system by a temperature or moisture content change(Figure 2.4). Equation(2.18)is based on the superposition of mechanical-,thermal-,and moisture-induced strains.Inversion of Equation(2.18)gives 5 Q12 (2.19) Consequently,the stress-generating strains are obtained by subtraction of the thermal-and moisture-induced strains from the total strains.The thermal- and moisture-induced strains are often approximated as linear functions of the changes in temperature and moisture concentration, e △T (2.20) 2 △M (2.21) ©2003 by CRC Press LLCequivalent to that for thermal strains [7,8] (neglecting possible pressure dependence of moisture absorption). The constitutive relationship, when it includes mechanical-, thermal-, and moisture-induced strains, takes the following form [1,4] (2.18) where superscripts T and M denote temperature- and moisture-induced strains, respectively. Note that shear strains are not induced in the principal material system by a temperature or moisture content change (Figure 2.4). Equation (2.18) is based on the superposition of mechanical-, thermal-, and moisture-induced strains. Inversion of Equation (2.18) gives (2.19) Consequently, the stress-generating strains are obtained by subtraction of the thermal- and moisture-induced strains from the total strains. The thermal￾and moisture-induced strains are often approximated as linear functions of the changes in temperature and moisture concentration, (2.20) (2.21) FIGURE 2.4 Deformation of a lamina subject to temperature increase. 1 2 12 11 12 12 22 66 1 2 12 1 T 2 T 1 M 2 M S S S S S ε ε γ σ σ τ ε ε ε ε             =                     +             +             0 0 00 0 0 σ σ τ εεε εεε γ 1 2 12 11 12 11 12 66 111 22 2 12 0 0 0 0           =           − − − −           Q Q Q Q Q T M T M 1 T 2 T 1 2 T ε ε α α         =      ∆  1 M 2 M 1 2 M ε ε β β         =         ∆ TX001_ch02_Frame Page 16 Saturday, September 21, 2002 4:48 AM © 2003 by CRC Press LLC